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Thursday, February 4, 2016

The Tricks in gratrixianum

Slipper Orchid pouches attract a lot of attention around here from our visitors. And so, from the Department of Frequently Asked Questions comes: Are Lady's Slipper Orchids carnivorous? Is the pouch a trap? 'No' and 'Sort of' are the answers. That glossy bubblicious pouch, actually a modified petal, is a trap for insects, but the trap has a different function from the traps of insectivorous plants. The pouch is just one of the parts of a pollination mechanism, a reproductive process in which a successful outcome is pollination, not nutrition. And the insect is the messenger, not the meal.

Paphiopedilum gratrixianum, a tropical Asian slipper flowering now in the Orchid Center, is an example. Tropical slipper orchids are thought to be pollinated by flies, though most of the evidence is indirect. There simply aren't a tremendous number of field studies documenting slipper orchid pollination. So, although I don't know exactly which insect pollinates Paphiopedilum gratrixianum, it's possible to make a fair guess, based on a study of a closely related species, Paphiopedilum villosum. A field study (Bänziger 1996) of P. villosum reported pollen capture by hover-flies and the author suggested that the hover-flies are lured by food deception.

The shimmering staminode (the flattened end of the column) in the center of the flower appears to mimic the sugary honeydew secretions of aphids. To a hover-fly, it holds the prospect of a meal. Something nutritious and delicious. But, no, it's simply a slippery surface, and the hover-fly falls into the pouch.

The margins of the pouch (above) are rolled inward and prevent the fly from taking wing. To escape, the fly has to climb the scaffolding of hairs behind the column where the pollen is located. The pollen sticks to the back of the fly as it emerges near the base of the column. The fly receives nothing that it can use, no supper, just a enormous blob of pollen that can be deposited at the next slipper orchid offering a fake meal.

Pollination using a food lure (real or fake) is a fairly common mechanism across the plant kingdom and involving different types of pollinators. But in orchids, the anatomy for deception and manipulation of winged insects has evolved to an extraordinary degree. Yes, the pouch is a trap, but in the same way that the bucket of a Coryanthes flower is a trap. It's a trap that facilitates pollination.

Monday, January 25, 2016

Snow Day

Paphiopedilum victoria-regina
We were spared Snowmageddon. The storm that paralyzed most of the East Coast stopped at our doorstep, hurled a handful of sleet at the greenhouse panes, and left. What a relief.

Not that we will be spared the fallout, though. Dozens of boxes of orchids for our Orchid Daze display are supposed to ship into east coast airports this week, a risky proposition that makes me break out in a sweat just thinking about it.

While I water, I wonder how our colleagues at botanical gardens in New York, Brooklyn, Washington and Virginia are faring. And Kennett Square, too, though I wonder if Longwood might not own more snowplows than the city of Atlanta. The problem facing any greenhouse grower under these circumstances (besides what's going on at home) is that greenhouse plants don't recognize snow days or weekends or holidays. There will always be plants that need water. Someone has to be there every single day. I can only hope that someone at each of these gardens lives close enough to walk in. And that the power stays on. And the back up generators fire up on cue.

Good luck to everyone having the 'Snow Day' experience. Stay safe.

Tuesday, January 19, 2016

Look What We Made

A rack of delicious Coryanthes macrantha seedlings, fresh from the lab.

These are going to be good! Stanhopea panamensis flowers smell like wintergreen. Two weeks out of the lab, the seedlings are getting established in trays in a humid low light greenhouse.

After about a month, we transfer seedlings to the main growing area in another greenhouse. This is a tray of Coryanthes alborosea less than a year old. They will soon be ready for individual pots.

A tasty batch of young Vanda barnesii.

To give them some elbow room as they grow, we remove every other seedling to another tray. Pescatoria coronaria has delectable red violet flowers.

Lemon flowers! Phalaenopsis mannii f. flava seedlings produce their first flowers while still in trays. We produce seedlings from species collection in order to rejuvenate our collection, to create material to install in our display areas, and to get rare material into the hands other botanical gardens and universities. As with baking, half the fun of creating is sharing.

Friday, January 15, 2016

Stanhopea tigrina

'Fierce' was the first word that came to mind when I saw this flower. Holding the heavy big boned flower in the palm of my hand gave me the unsettling sensation that I was holding the skull of an enormous hook-beaked raptor. No wonder people go gaga when they see Stanhopea tigrina.

Stanhopea tigrina is endemic to Mexico, where it grows on the eastern slopes of the Mexican plateau at elevations up to 1800 meters. We have a number of tigrina accessions of different provenance, all growing in our intermediate (60º night minimum) greenhouse, all doing reasonably well. However, this winter, on a trial basis, I'm moving some them to a greenhouse with cooler night temperatures for three months, to see if their growth improves.
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With the column removed, you can get a good look at the broad lip with its massive horns.


Even the column is impressive as you can see in this close up -conspicuously winged and splashed with red. Stanhopea tigrina isn't rare in cultivation, but most people would consider themselves lucky to have seen one. You can see our plants in the Orchid Display House. They flower off and on in late summer and early fall. The flowers last about three days.


Monday, January 4, 2016

Acianthera prolifera

We shouldn't be growing this. We shouldn't even try. Andy Phillips should be growing this in Encinitas, California. Acianthera prolifera is one of those orchids. The ones that want hot dry days and cool nights. The ones that go belly up here in summer. We excel at hot humid days and hot humid nights. April and October are the only months when an Atlanta greenhouse achieves the California greenhouse grail.

And yet, this plant thrives in our back up greenhouse. There must be enough variability in the environmental parameters of its natural range -the area around Bahia, Brazil, Venezuela and Guyana at 1300 to 1600 meters- that allow it to thrive as a slightly dry epiphyte in an intermediate to warm greenhouse in bright light. And that's terrific, because I'm completely smitten with those thick, rough textured leaves that are bright green and shaped like shallow bowls. And the chain of aubergine flowers that open just wide enough for a tiny fly pollinator. I think this plant will do reasonably well as an epiphyte in a bright location about six feet from the ground in our Orchid Display House, so be sure to look for it this spring.

Sunday, January 3, 2016

Welcome 2016

Christmas Day and New Year's Day have a unique feeling of solitude and tranquility here, at least for our staff. They are the only regular days when we are closed during the daylight hours, and therefore the only time when we aren't rushing to finish watering and clean up by 9 am. It allows us (the handful of horticulturists on watering duty) the luxury of pausing to relax in our surroundings. Here are a few things that caught my eye on New Year's Day.
Laelia anceps growing on rocks in the Mexico bed
The enormous (three foot) leaves of Anthurium warocqueanum
A random spattering of spots on the dorsal sepal of Paphiopedilum exul
Begonia bipinnatifida with wonderfully dissected leaves
The lovely pink pouches of Phragmipedium Cape Sunset
Phragmipedium schlimii and P. besseae flowering on the waterfall in the Tropical High Elevation House
Cavendishia micayensis (a tropical blueberry) flowering next to the striped leaves of Vriesea splendens
Jason Ligon watering the Tropical High Elevation House on New Year's Day
The Phalaenopsis Blast in the Orchid Display House
Have a wonderful new year! Garden Lights Holiday Nights runs every night through January 10, but there is plenty to see during the daytime, too. Come and relax in the warmth of the Fuqua Conservatory and the Fuqua Orchid Center!

Tuesday, December 29, 2015

Stanhopea platyceras

It's not very often that we have two different clones of the spectacular Stanhopea platyceras flowering in close proximity, so this was a good opportunity for comparison. It's easy to forget how variable some species can be. ABG 20041565 has a long narrow hypochile that is relatively lightly spotted.

The second clone, ABG 20140724, has a stouter hypochile with spots that have almost coalesced into a deep purple (intensified in this flower after day three). Platyceras means 'broad flat horns', a characteristic that is more striking in the second clone.

Stanhopea platyceras flowers are big (4 inches across) and almost everyone who sees them stops for a second look. They seemed to be the most photographed orchids in the Orchid Center when they flowered. Stanhopea platyceras is endemic to Colombia, according to Rudolf Jenny, where it grows at 1000 to 1500 meters elevation. We grow our plants in an intermediate greenhouse in 70% shade. I'm happy to report two capsules developing on 20041565, the result of selfings. One capsule will go to the lab for seedling production, the other will be photographed.

Monday, November 30, 2015

Garden Lights Holiday Nights

Ready for some holiday sparkle? Garden Lights Holiday Nights returns this year with a dazzling show. Here are some scenes from this year's holiday installation in our glasshouses.

A tide of Jubilee Pink poinsettias (Euphorbia pulcherrimea 'Jubilee Pink') in the Conservatory Lobby ready for installation on the vertical wall.


White Moth orchids (Phalaenopsis) against a sparkling backdrop of lights in the Conservatory Lobby.

The vertical wall in the Conservatory Lobby has a checkerboard pattern of pink and red poinsettias and white Kalanchoe.

The Poinsettia Tree in the Orchid Atrium has vertical stripes of red poinsettia and Aglaonema.

Jason carries one of the Freedom Red poinsettias (Euphorbia pulcherrima 'Freedom Red').

An icy blue combination of Silver Buttonwood (Conocarpus erectus var. sericeus), White Amaryllis (Hippeastrum Wedding Dance'), Nerve Plant (Fittonia argyronuera) and Sansevieria 'Bantel Sensation'. Our show was designed by Tres Fromme, ABG's Landscape and Design Manager.

The Three Bears doing the Lindy in the Orchid Display House. Their elegant Roaring '20's costumes were created by Kimberly McAllister.



Double Pink Kalanchoe (Kalanchoe blossfeldiana 'Jodi') in the Orchid Display House.

Satin Pothos (Scindapsus pictus 'Argyraeus') is the groundcover below the Three Bears.

Long nights and dark days almost demand illumination and music. Bring your family! Garden Lights Holiday nights opens nightly at 5 pm through January 9.

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